GB1360468A - Digital display system for a floating point number - Google Patents

Abstract

1360468 Display device OMRON TATEISI ELECTRONICS CO 24 Nov 1971 [25 Nov 1970] 54589/71 Heading G4A A digital display, e.g. for use in a desk top calculator, includes M digit display devices and associated decimal point displays and an indicator arranged to display X10<SP>n</SP>, the display being fed with a decimal number indicative of the position of the decimal point in the number to be displayed and being arranged, when the decimal point indicating number is equal to or exceeds n, to activate the X10<SP>n</SP> indicator and display. The decimal point n places to the left of the position indicated by the position indicating number. In an embodiment the M most significant digits are displayed and a signal indicating the position of the decimal point is fed to a register having a capacity of M. If the register overflows the index display 10<SP>n</SP> is lit and n is subtracted from the contents of the register using an adder or a further register. The decimal point indieating register may be replaced by series connected counters using the octal system if n = 8. The resulting decimal point indication in the register lights a decimal point indicator at the appropriate position in the M digit display. In a further embodiment the decimal point indication is stored in a recirculating shift register. As described n = 8 and the fourth stage of the register (= 8) is connected to the 10<SP>8</SP> index indicator, the remaining stages being connected via a decoder to the decimal point indicators. Thus if the number to be displayed has more than 8 integral digits the 10<SP>8</SP> index indicator is automatically lit and the remaining shift register stages provide the correct decimal point indication. The system may be extended, e.g. by providing a 10<SP>16</SP> index indicator operated by an additional shift register stage. The 10<SP>8</SP> and 10<SP>16</SP> index indicators may be lit simultaneously where a number to be displayed has 24 or more integer digits. The Specification states that a static shift register may be used in place of the recirculating unit described above. As described, Fig. 6 (not shown) the decimal point indicating shift register includes a section storing the decimal point indication and a section storing the number to be displayed and is connected via gates to two further shift registers within the desk top calculator. In yet a further embodiment, Fig. 8, the above arrangement is modified by the provision of a gating circuit which acts so that if the fourth shift register stage of the decimal point indicator contains a 1 and the remaining stages all 0's the 10<SP>8</SP> index indicator is not lit, the decimal point being displayed at the end of the M(=8) digit display. However if the fourth stage contains a 1 and any other one of the stages contains a 1 then the 10<SP>8</SP> index indicator is illuminated and the decimal point in the digit display is controlled by only the other stages. The Specification states that the display may be a printer.